This invention relates to solenoid operated fuel injectors used to control the injection of fuel into an internal combustion engine.
It is known in the fuel injection art to utilize a spherical valve ball within a solenoid operated fuel injector to close a fuel passageway in the injector. In such injectors, it is common to fabricate a flat on the ball valve and use the ball in combination with a collar that provides an annular cradling surface for the ball. A spring disc interfaces with the ball and urges the ball into an open position. Fuel is communicated around an armature and through the spring disc to establish fuel flow when the ball is in an unseated position. The ball must be guided to center itself on a seat of the fuel passageway and the armature requires a surface to keep the ball at least proximately concentric within the axis within the radial confinement imposed on the ball by the tip end of the armature.
With such assemblies, the dynamic flow rate of the fuel is set through the spring rate and selecting the spring becomes critical. These injectors require a non-magnetic plug in the bottom of their armatures to reduce wear and have a coil that is contacted by the fuel.
According to the present invention, a fuel injector is divided into two subassemblies. Each of the subassemblies are individually put together, and then the subassemblies are fastened to assemble the fuel injector.
The present invention provides a fuel injector for use with an internal combustion engine. The fuel injector comprises a valve group subassembly and a coil group subassembly. The valve group subassembly includes a valve body extending along a longitudinal axis; a valve seat secured to the valve body, the valve seat defining an outlet opening through which fuel flows; an armature movable along the longitudinal axis with respect to the valve body; a valve ball fixed to the armature, the valve ball being moved between an open position wherein the valve ball is spaced from the valve seat such that fuel flow through the outlet opening is permitted and a closed position wherein the valve ball contiguously engages the valve seat such that fuel flow is prevented; and a first fastening feature. The coil group subassembly includes a solenoid coil operable to displace the armature with respect to the valve body; and a second fastening feature matingly engaging the first fastening feature on the valve group subassembly.
The present invention further provides a method of assembling a fuel injector for use with an internal combustion engine. The method comprises assembling a valve group subassembly including fixing a closure member to an armature; assembling a coil group subassembly; and fastening together cooperating fastening features on the valve group subassembly and the coil group subassembly.